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Vulnerability · Published Jul 27, 2026 · Assigned by Linux

CVE-2026-64538ipv6: Fix null-ptr-deref in fib6_nh_mtu_change().

Unrated

In plain English

A security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 10% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS )–Not rated
Exploit odds (30 days)0.2%top 90.0% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

In the Linux kernel, the following vulnerability has been resolved: ipv6: Fix null-ptr-deref in fib6_nh_mtu_change(). fib6_nh_mtu_change() re-fetches idev via __in6_dev_get(arg->dev) and dereferences idev->cnf.mtu6 without a NULL check. addrconf_ifdown() clears dev->ip6_ptr with RCU_INIT_POINTER() after rt6_disable_ip() has released tb6_lock, so the RA-driven MTU walk can observe a NULL idev and oops. The caller rt6_mtu_change_route() guards its own __in6_dev_get(), but this re-fetch is unguarded; nexthop-backed routes survive addrconf_ifdown()'s flush, so the walk still reaches it after ip6_ptr is nulled. Return 0 when idev is NULL, matching rt6_mtu_change_route() and the fib6_mtu() fix in commit 5ad509c1fdad ("ipv6: Fix null-ptr-deref in fib6_mtu()."). Oops: general protection fault, ... KASAN: null-ptr-deref in range [0x00000000000002a8-0x00000000000002af] RIP: 0010:fib6_nh_mtu_change+0x203/0x990 rt6_mtu_change_route+0x141/0x1d0 __fib6_clean_all+0xd0/0x160 rt6_mtu_change+0xb4/0x100 ndisc_router_discovery+0x24b5/0x2cb0 icmpv6_rcv+0x12e9/0x1710 ipv6_rcv+0x39b/0x410

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.180-1DEBIAN-CVE-2026-64538
Debian:13linux6.12.100-1DEBIAN-CVE-2026-64538
Debian:14linux7.1.5-1DEBIAN-CVE-2026-64538
Debian:12linux-6.126.12.100-1~deb12u1DEBIAN-CVE-2026-64538
Ubuntu:22.04:LTSlinux5.15.0-198.208UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux6.8.0-147.147UBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux7.0.0-38.38USN-8887-1
Ubuntu:26.04:LTSlinux7.0.0-38.38UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-aws5.15.0-1117.124UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-aws6.8.0-1067.70UBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-aws7.0.0-1014.14USN-8887-1
Ubuntu:26.04:LTSlinux-aws7.0.0-1014.14UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-aws-6.17no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-aws-6.8no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-aws-7.07.0.0-1014.14~24.04.1USN-8887-2
Ubuntu:24.04:LTSlinux-aws-7.07.0.0-1014.14~24.04.1UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-azure5.15.0-1123.132UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-azure6.8.0-1071.79UBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-azure7.0.0-1017.17USN-8888-1
Ubuntu:26.04:LTSlinux-azure7.0.0-1017.17UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-azure-6.17no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-azure-6.8no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-azure-7.07.0.0-1017.17~24.04.1UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-azure-7.07.0.0-1017.17~24.04.1USN-8888-2
Ubuntu:22.04:LTSlinux-azure-fde5.15.0-1122.131UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-azure-fde6.8.0-1069.76UBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-azure-fde7.0.0-1016.16USN-8888-1
Ubuntu:26.04:LTSlinux-azure-fde7.0.0-1016.16UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-azure-fde-6.17no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-azure-fde-6.8no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-azure-fde-7.07.0.0-1016.16~24.04.1USN-8888-2
Ubuntu:24.04:LTSlinux-azure-fde-7.07.0.0-1016.16~24.04.1UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-azure-nvidiano fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-gcp5.15.0-1118.128UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-gcp6.8.0-1071.79UBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-gcp7.0.0-1014.14USN-8887-1
Ubuntu:26.04:LTSlinux-gcp7.0.0-1014.14UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-gcp-6.17no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-gcp-6.8no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-gcp-7.07.0.0-1014.14~24.04.1UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-gcp-7.07.0.0-1014.14~24.04.1USN-8887-3
Ubuntu:22.04:LTSlinux-gke5.15.0-1113.119UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-gke6.8.0-1066.74UBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-gke7.0.0-1008.9USN-8887-1
Ubuntu:26.04:LTSlinux-gke7.0.0-1008.9UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-gkeop5.15.0-1100.108UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-gkeop6.8.0-1052.56UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-hwe-6.17no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-hwe-6.8no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-hwe-7.07.0.0-38.38~24.04.4UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-hwe-7.07.0.0-38.38~24.04.4USN-8887-3
Ubuntu:22.04:LTSlinux-ibm5.15.0-1111.115UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-ibm6.8.0-1067.68UBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-ibm7.0.0-1015.15USN-8887-1
Ubuntu:26.04:LTSlinux-ibm7.0.0-1015.15UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-ibm-6.8no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1112.118UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-kvm5.15.0-1109.114UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-195.205UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-lowlatency6.8.0-147.147.1UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.8no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-nvidia5.15.0-1112.113UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-nvidia-6.17no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-nvidia-6.8no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-nvidia-7.07.0.0-1024.25~24.04.1USN-9003-1
Ubuntu:24.04:LTSlinux-nvidia-7.07.0.0-1024.25~24.04.1UBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-nvidia-bos7.0.0-2022.23UBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-nvidia-bos7.0.0-2022.23USN-9003-1
Ubuntu:24.04:LTSlinux-nvidia-lowlatencyno fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-nvidia-tegra5.15.0-1070.72UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-nvidia-tegrano fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-nvidia-tegra-igx5.15.0-1059.59UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-oem-6.17no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-oem-7.07.0.0-1015.15UBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-oem-7.07.0.0-1015.15USN-8889-1
Ubuntu:22.04:LTSlinux-oracle5.15.0-1114.120UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-oracle6.8.0-1064.67UBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-oracle7.0.0-1013.13USN-8887-1
Ubuntu:26.04:LTSlinux-oracle7.0.0-1013.13UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-oracle-6.17no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-oracle-6.8no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-oracle-7.07.0.0-1013.13~24.04.1UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-oracle-7.07.0.0-1013.13~24.04.1USN-8887-3
Ubuntu:22.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-realtime7.0.0-38.38.1USN-8887-1
Ubuntu:26.04:LTSlinux-realtime7.0.0-38.38.1UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-64538
Ubuntu:26.04:LTSlinux-riscv7.0.0-38.38.1UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-riscv-6.17no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-riscv-6.8no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-riscv-7.07.0.0-38.38.1~24.04.1UBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-vmware6.8.0-1008.8UBUNTU-CVE-2026-64538
Ubuntu:24.04:LTSlinux-xilinxno fix listedUBUNTU-CVE-2026-64538
Ubuntu:22.04:LTSlinux-xilinx-zynqmp5.15.0-1080.84UBUNTU-CVE-2026-64538

Affected products (as reported)

VendorProductVersions
Linux Linux c0b220cf7d80eb8a36ae9f12cae6df4577a6814e – before d08d019f2f43a6f9a71e81868bbc326b3afaf37bc0b220cf7d80eb8a36ae9f12cae6df4577a6814e – before 1451deca9896957159f0666520a792c1b861af4fc0b220cf7d80eb8a36ae9f12cae6df4577a6814e – before b2c70dd3326809429b709a9c7e9220d29923051ac0b220cf7d80eb8a36ae9f12cae6df4577a6814e – before 302d57ed7872838b40e56a868fb4c7da7da606e9c0b220cf7d80eb8a36ae9f12cae6df4577a6814e – before 80600b5d0f3ecb9324120dc95b5e915130f516c5c0b220cf7d80eb8a36ae9f12cae6df4577a6814e – before b0d0eb13a0441a8ebf4f227843deaf494f1e2c33c0b220cf7d80eb8a36ae9f12cae6df4577a6814e – before 6428634f7a0b7878144b4925c37856bef3224967c0b220cf7d80eb8a36ae9f12cae6df4577a6814e – before 46c3b8191aad3d032776bf3bebf03efdf5f4b905
Linux Linux 5.3

References